It has been customary for some time to clean carpets by spraying a cleaning fluid, usually a warm solution of detergent and water, onto a narrow strip of the carpet and immediately thereafter vacuuming the strip to carry away the liquid and the loosened dirt. The cleaning fluid spray nozzle has usually been mounted on or closely associated with the vacuum nozzle in a wand or housing which is drawn across the carpet toward the operator. Examples of apparatus employing this technique are disclosed in U.S. Pat. Nos. 3,974,541, granted Aug. 17, 1976 to Donahue B. Silvis and Edward A. Vargas, for "APPARATUS FOR CLEANING A FLOOR" and No. 4,649,594, granted Mar. 17, 1987 to Dale L. Grave, for "CLEANING HEAD FOR SMOOTH AND NAPPED SURFACE COVERING MATERIALS".
Carpet cleaning apparatus of the aforementioned type usually are capable of cleaning only a narrow strip of carpet on each pass so cleaning with them is time consuming. Furthermore, because the movement of the vacuum nozzle is unidirectional, there is a tendency for the apparatus to mat down the wet carpet nap trapping dirt therein. This simply means that the apparatus does not clean the carpet as thoroughly as is desired.
Hydra Master Corporation of West Lynnwood, Washington produced and sold an RX-20 Rotary Jet Extraction System in which five cleaning heads, each with a spray jet and a vacuum head, were mounted for rotary motion in a housing. This apparatus not only matted the carpet but also subjected the carpet to excessive wear during cleaning.
James J. Rose and Edward L. Horton in their U.S. Pat. No. 4,037,290, granted July 26, 1977 for "VACUUM CLEANING DEVICE" proposed to loosen and remove soil from the carpet simply by directing a rotating jet of high pressure air into the carpet beneath a movable vacuum chamber. So far as is known, the invention disclosed in that patent never enjoyed any commercial success.
As early as 1930, Carl P. Brockway proposed in his U.S. Pat. No. 1,766,425, for "VACUUM SWEEPER" that the vacuum nozzle of a conventional vacuum cleaner be oscillated in a forward and backward direction. His objective was to cause the threads of the fabric to vibrate more or less rapidly to loosen and dislodge dirt particles.
U.S. Pat. No. 4,095,309, granted June 20, 1978 to John J. Sundheim for "APPARATUS FOR CLEANING A CARPET" suggested reciprocating a single cleaning head (comprising spray nozzles and a vacuum nozzle) in relation to the body of the apparatus. This apparatus has the obvious disadvantage of exhibiting severe imbalance in operation. The inventor sought to employ the unbalanced jerking motion of his components to propel the apparatus over the carpet. As a result, the movement of the cleaning head relative to the carpet was essentially unidirectional, albeit intermittent, offering the same tendency to mat the carpet nap.
There continues to be a need for truly effective carpet cleaning apparatus.